Cement admixtures comprising a polycarboxylic acid polymer have been widely used for cement compositions such as cement paste, mortar, and concrete. They are now essential in constructing civil engineering and building structures and the like from a cement composition. Such cement admixtures are used as a water reducing agent and the like. They increase the fluidity of cement compositions to thereby reduce the water requirement of the cement compositions and therefore are effective in improving the strength, durability, and the like, of hardening products. As such water reducing agents, polycarboxylic acid water reducing agents comprising polycarboxylic acid polymers as main component, which are superior in water-reducing performance to naphthalene and other conventional water reducing agents, have already led to good results in many cases as air-entraining and high-range water-reducing admixture.
However, cement admixtures are required to be able not only to show water-reducing performance in such cement compositions but also to improve cement compositions in viscosity to thereby facilitate the works at the sites of handling them. Thus, they are required at the sites of civil engineering and building structure construction not only to be able to show water-reducing performance but also to provide a viscosity in such the level that the works will be facilitated at the sites of handling them. If a cement admixture can exhibit such performance characteristics, it will improve the working efficiency in civil engineering and building structure construction.
With respect to such requirements, Japanese Kokai Publication Hei-09-248438 proposes a dispersant for decreasing the viscosity of hydraulic compositions such as cement. However, in construction sites, it is required to make cement compositions easier to be handled, and have improved basic performances. Thus, it has been asked for providing cement admixtures satisfying such requirements.